Patent Document 1 discloses a grill shutter device that can control the flow rate of air flowing from grill opening into an engine compartment according to opening and closing operations of shutter mechanism provided in the grill opening in the front portion of a vehicle body.
In the grill shutter device, for example, when the vehicle is travelling at high speed, the shutter mechanism is closed and the air flowing into the engine compartment is limited so that the aerodynamic performance (such as Cd value) of the vehicle can be improved. When starting the engine, the flow rate of the air introduced into the radiator is limited so that the warm-up time of the engine is reduced. Further, when the engine temperature tends to be increased, the shutter mechanism is opened so that the flow rate of the air flowing into the engine compartment is increased. Accordingly, the engine temperature is appropriately controlled.
Generally, such a grill shutter device is configured to open the shutter mechanism after usual opening and closing controls of the shutter mechanism is completed by turning off the ignition switch. That is, the shutter mechanism is closed when the vehicle is in the stopped state. This restricts the shutter mechanism from being stuck into the closed state. Further, Patent Document 1 discloses a configuration for forcibly terminating the opening and closing controls of the shutter mechanism to open the shutter mechanism when the voltage supplied to the driving motor of the shutter mechanism is reduced. This avoids the situation in which the amount of the air flowing into the vehicle is insufficient due to the stuck closed state of the shutter mechanism as described above.